the effect of antioxidant vitamin supplementation on muscle performance and redox status after eccentric training

Conditions: Muscle Damage; Oxidative Stress; Hemolysis

Summary: consumption of vitamin supplements is a common practice among athletes or people participating in health promoting exercise programs. the reason for this interest in vitamin supplements is primarily because of the observation that enhanced production of reactive oxygen and nitrogen species (rons) influence fundamental biological processes, such as gene expression, signal transduction and enzyme activity. in a muscle and exercise physiology context, a low level of rons is required for normal force production, whereas marked increases in rons can cause contractile dysfunction, resulting in muscle weakness and fatigue. on the other hand rons are involved in signaling pathways and serve to up-regulate the expression of a number of genes and can exert favorable effects such as training adaptations. the present study will employ a valid eccentric exercise model to examine the influence of combined vitamin c and e supplementation after acute and chronic eccentric exercise on muscle damage and performance, redox status, hemolysis and lipid and lipoprotein profile.

historically there was a shift in the paradigm regarding the effects of antioxidant supplementation on muscle performance and redox status. in fact, back in the 80's and 90's most of the relevant studies reported "positive" effects of antioxidant supplementation on muscle performance, muscle damage and redox status. on the other hand, the last five years, an increasing number of well-received studies are appearing pointing towards the negative impact of antioxidant supplementation. moreover, much more studies than the past are now specifically addressing the effects of antioxidant supplementation on the exercise adaptations that take place after chronic exercise. regarding the latter, it has been reported recently that antioxidant supplementation greatly decreases training efficiency and prevents many cellular adaptations to chronic exercise. nevertheless, the debate is still open and an equal number of recent studies have reported the reverse i.e. positive effects of antioxidant supplementation on exercise adaptations or virtually no effect of antioxidant supplementation on exercise adaptations. eccentric muscle work is an essential part of daily activities of humans, such as walking, and in particular, when walking downhill or descending stairs. the most notable and well-described effect of eccentric exercise is the muscle damage that peaks one to three days after exercise. eccentric exercise can cause effects other than just muscle damage, from activation of several transcription factors to favorable changes on lipid and lipoproteins profile. in a double-blinded fashion, men will receive either a daily oral supplementation of vitamin c (1g) and vitamin e (400iu) or placebo for eleven weeks. following baseline tests, volunteers will have to perform an eccentric exercise session two times per week for four weeks. before and after the chronic eccentric exercise volunteers will be subject to one session of acute eccentric exercise, and physiological measurements will be performed as well as blood samples and muscle biopsies will be collected. the aims of the present research are to investigate: * the effect of antioxidant vitamin supplementation for 4 weeks on muscle performance, redox status, hemolysis and lipids and lipoprotein profile, * the effect of an acute bout of eccentric exercise on muscle performance, redox status, hemolysis and lipid and lipoproteins profile of untrained individuals supplemented with or without antioxidant vitamins, * the effect of 4 weeks of eccentric training on muscle performance, redox status, hemolysis and lipid and lipoproteins profile of untrained individuals supplemented with or without antioxidant vitamins, * the effect of an acute bout of eccentric exercise on muscle performance, redox status, hemolysis and lipid and lipoproteins profile of individuals trained for 4 weeks and supplemented with or without antioxidant vitamins.

Eligibility criteria:
inclusion criteria: * physiological body mass index (bmi) * physiological health profile * subject provides written informed consent exclusion criteria: * smoker * professional athlete * consumed any nutritional supplement the last 3 months * performed pure eccentric exercise the last 6 months * non caucasian

Keywords: eccentric training free radicals antioxidant supplements training adaptations lipid profile